We claim the ornamental design for a document feeder, as shown and described.
FIG. 1 is a top, front, left side perspective view of a document feeder;
FIG. 2 is a top, front, right side perspective view thereof;
FIG. 3 is a top view thereof;
FIG. 4 the front view thereof;
FIG. 5 is a left side view thereof; and,
FIG. 6 is a right side view thereof.
The evenly-spaced broken lines depict environmental subject matter and the unevenly-spaced broken lines depict the boundaries of the design, neither of which form any part of the claimed design.